Among the following, the correct statement is 

Let us review the given statements.

            a) It is not true because a body which is having constant velocity will maintain both magnitude and direction as constant so there is no chance for varying speed.

            b) It is true because a body moving with constant speed can produce no displacement while  moving in a circular path with constant speed its displacement will become zero after

    completing every revolution.

            c) It is not true because while moving with constant speed in a circular path body will gain acceleration.

    d) It is true because while moving in a curved path or circular path a body can produce

            varying velocity from one point to another point.